Children are thought to comprise at least 11% of the 9.4 million annual cases of tuberculosis (TB) worldwide. The lack of accurate diagnostics for pediatric TB significantly hinders the ability to detect and treat the disease in this vulnerable population. As a result, many children in TB-endemic regions like Tanzania present with advanced illness and suffer undue morbidity and mortality. The project proposed in this application, Improving pediatric TB diagnosis and management in Tanzania, will evaluate a new diagnostic assay, the Antibodies in Lymphocyte Supernatant (ALS), with the hypothesis that immature activated B cells circulate in response to TB antigens which are present during TB disease and not latent TB infection; these plasmablasts disappear with the resolution of TB. A prospective cohort will be established, comprised of children presenting to Haydom Lutheran Hospital in Tanzania with suspected TB. Children will be followed forward in order to best confirm their illness as TB versus not-TB based upon World Health Organization and NIH/NIAID criteria using clinical, radiographic and microbiological parameters, with the added requisite of having a confirmed alternative diagnosis to be classified as a non-TB patient. Additional confirmatory testing will be pursued through acid-fast bacillus smear, mycobacteriologic culture, and molecular testing via the GeneXpert MTB/RIF test. The performance of the ALS assay and GeneXpert as diagnostic tests for TB will be evaluated among TB and non- TB patients. Additionally, a nested case control study will be performed to examine outcomes within TB cases. Children will be classified into normal responders or slow responders based on changes in clinical, radiographic, and microbiological parameters adapted from adults. The performance of ALS as a biomarker will be compared between normal and slow responders. Risk factors for slow treatment response will be investigated including drug-resistant TB, serum drug levels to the two most potent first-line TB medications (isoniazid and rifampin), HIV status, nutritional status and concurrent diarrheal illness. The career development plan which will enhance the success of the stated objectives combines graduate level courses in epidemiology, biostatistics, and immunology, as well as seminars on pharmacokinetics of TB medications and patient oriented research in TB diagnostics. Laboratory skills, including mastery of ALS methodology, will be pursued. My team of mentors collectively has expertise in clinical TB, TB diagnostics research, pediatric TB immunology, pharmacokinetics of TB medications, international health research and biostatistics. Structured oversight and guidance from my mentors will provide the scientific background, experiential training, and tools required to conduct patient-oriented research with sound clinical design, execution and interpretation that benefits children with tuberculosis in resource-limited settings.